[Xastir] Tracking with Xastir using NMEA tracker

[Jason KG4WSV]

On Mon, Jul 3, 2017 at 11:00 AM, Kurt <ksaves2 at sbcglobal.net> wrote:
> I've been trying to get some of the electronics oriented rocket guys to come up with ham band NMEA trackers that would have better range and just inject a callsign here and there in an NMEA string.

see attached.  It speaks APRS (TNC-2 style packets, but in ASCII, like APRS-IS).

It's 250mW and I don't usually drop packets, but the GPS often drops a
few during boost - vertical velocity is too fast for it.

and it fits in a 38mm nosecone.  The blue thing is a 3d printed
bulkhead that fits a madcow 38mm PC nosecone (just add a couple of
countersunk holes).

> Before you APRS people get yanked,

This is the xastir list, not the APRS list. :)

>We like to use high rate tracking as one position every 5 seconds

I routinely operate at 1Hz.  Right now I'm sending a packet every 3s
with timeslotting so I can have multiple units on the air at the same
time (think 2 stage). since it's 9600 baud or 19.2k baud over the air,
I should be able to easily get 2 packets a second, but that puts some
timing requirements on my little tracker processor and I haven't done
the work (e.g. i may need the GPS PPS signal connected).

You can also run multiple receivers - e.g. an omni and a yagi - and
xastir will handle the deduplication.

I wish I could get APRX to digi it to 70cm for me (so I can see it on
the Kenwood HT) without hacking the source, but no joy.  No one wants
to digi a TNC2 packet,  not even an original copy.  I'm thinking I'll
give up on that and just let xastir igate it for me, since that's
simpler than anything else i've come up with.  I really don't want the
tracker to speak KISS, because it's trivial to get coordinates with a
receiver and a terminal application they way it's working now.

I've thought about adding vertical velocity, or even 3d velocity, but
that's on down the list. It could be nice to have some verification
other than visual that something came apart at apogee.

I've also thought about connecting xastir's festival output to a
transmitter - who needs a Kate for $1000?

-Jason
kg4wsv